Re: SMP/cc Cluster description

Alan Cox
2001-12-06T22:50:06Z

> > ftruncate
>
> I'm not sure what the point is. We've already agreed that the multiple OS
> instances will have synchonization to do for file operations, ftruncate
> being one of them.
>
> I thought the question was how N user processes do locking and my answer
> stands: exactly like they'd do it on an SMP, with mutex_enter()/exit() on
> some portion of the mapped file. The mapped file is just a chunk of cache

ftrucate invalidates that memory under you, on all nodes. That means you do
end up needing cross node locking and your file operations simply won't lie
down and scale cleanly